There is a need for an efficient catalytic process to manufacture alcohols from light olefins to augment the supply of high octane blending stocks for gasoline. Lower molecular weight alcohols such as isopropyl alcohol (IPA) are in the gasoline boiling range and are known to have a high blending octane number. In addition, by-product propylene from which IPA can be made is usually available at low cost in a petroleum refinery.
The catalytic hydration of olefins to provide alcohols is a well-established art and is of significant commercial importance. Representative olefin hydration processes are disclosed in U.S. Pat. Nos. 2,162,913; 2,477,380; 2,797,247; 3,798,097; 2,805,260; 2,830,090; 2,861,045; 2,891,999; 3,006,970; 3,198,752; 3,810,849; 3,989,762, among others.
Olefin hydration employing zeolite catalysts is known. As disclosed in U.S. Pat. No. 4,214,107, monoolefins in the C.sub.2-4 range, specifically, ethylene, propylene, n-butene-1 and cis and trans n-butene-2, are reacted with water at olefin:water mole ratios of from about 0.1:1 to 2:1, preferably from about 0.5:1 to 1.5:1 (equivalent to water:olefin mole ratios of from about 10:1 to about 0.5:1 and preferably from about 2:1 to about 0.67:1) to provide the corresponding alcohol, essentially free of ether and hydrocarbon by-product, employing as olefin hydration catalyst a zeolite having a Constraint Index of 1 to 12 as exemplified by ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38. Of the foregoing zeolites, only acidic ZSM-5 is illustrated in a working example.
According to U.S. Pat. No. 4,499,313, an olefin is hydrated to the corresponding alcohol in the presence of hydrogen-type mordenite or hydrogen-type zeolite Y each having a silica-alumina molar ratio of 20 to 500. The use of such a catalyst is said to result in higher yields of alcohol than olefin hydration processes which employ conventional solid acid catalysts. Use of the catalyst is said to offer the advantage over ion-exchange type olefin hydration catalysts of not being restricted by the hydration temperature. Reaction conditions employed in the process include a temperature of from 50.degree.-300.degree. C., preferably 100.degree.-250.degree. C., a pressure of 5 to 200 kg/cm.sup.2 to maintain liquid phase or gas-liquid multi-phase conditions and a mole ratio of water to olefin of from 1 to 20. The reaction time can be 20 minutes to 20 hours when operating batchwise and the liquid hourly space velocity (LHSV) is usually 0.1 to 10 in the case of continuous operation.
European Patent Application 210,793 describes an olefin hydration process employing a medium pore zeolite as hydration catalyst. Specific catalysts mentioned are Theta-1, said to be preferred, ferrierite, ZSM-22, ZSM-23 and NU-10.